The camera is balanced for daylight, where it is anticipated that 90% of pictures are going to be taken. Taking pictures in artificial light will result in a yellow/red cast. The use of the flash should counterbalance this effect. Underexposure will also exaggerate the effect.

In a simple camera as is fitted in the iPhone, nothing can be done "in camera" the only way of correction is with something like Photoshop. However, there may be Apps that will do the job.

A firmware update is out of the question because if the camera was rebalanced for artificial light, all photos taken in daylight would suffer from a blue cast!!